Femtosecond laser–assisted cataract surgery and conventional phacoemulsification cataract surgery are both proinflammatory through the disruption of the blood–aqueous barrier,1 and posterior capsule opacification (PCO) is a common complication affecting visual acuity.2 Posterior capsule opacification is commonly treated with neodymium:YAG (Nd:YAG) capsulotomy, and it remains unclear whether there is a difference in the rate of Nd:YAG laser capsulotomy between the 2 procedures.3 We examined the long-term incidence of symptomatic PCO requiring treatment with Nd:YAG laser in consecutive eyes having femtosecond laser–assisted cataract surgery and phacoemulsification cataract surgery. Symptomatic PCO was defined as patients who had blurred vision in the presence of visible PCO with a drop in visual acuity of one line or more from their previous acuity.
PATIENTS AND METHODS
In this longitudinal comparative cohort study, cases were obtained from the Launceston Eye Institute, Launceston, Tasmania, Australia, and have been reported (as part of subset Center A) by Ewe et al.4 The study was approved by the Tasmanian Human Research Ethics Committee (HREC H12534) and was performed in accordance with the tenets of the Declaration of Helsinki.
Femtosecond laser–assisted cataract surgery was chosen by the patients on the basis of their ability to pay the extra costs associated with the procedure; otherwise, phacoemulsification cataract surgery was performed. Femtosecond laser–assisted cataract surgery was performed using the Catalys Precision Laser System (Johnson & Johnson). Postoperatively, patients were reviewed in the clinic at 1, 6, and 12 months, and beyond as clinically indicated. All patients were educated about PCO with verbal and written information on discharge and were asked to return to the clinic if a decrease in visual acuity was noted.
Neodymium:YAG capsulotomy–related data were collected retrospectively from Launceston Eye Institute's electronic database in October 2017. Patients were followed for 5 years after surgery. Study data were imported into Stata software (version 15, Statacorp LLC) for analysis. Cross tabulations with chi-square tests were used to evaluate differences in categorical data and independent t tests for age. Kaplan-Meier survival curves were generated for time to Nd:YAG capsulotomy. Right-censoring was accounted for in the data for patients who did not have Nd:YAG within 5 years' follow-up and for those lost to follow-up. For patients lost to follow-up, the date of censoring was the date of final clinical appointment. A P value less than 0.05 was considered significant for all tests.
Of the 1002 eyes included in the study, 319 eyes had femtosecond laser–assisted cataract surgery and 683 eyes had phacoemulsification cataract surgery. An Nd:YAG laser posterior capsulotomy was performed in 193 eyes (60.5%) and 426 eyes (62.4%), respectively. The Kaplan-Meier survival curves showed very similar times from surgery to Nd:YAG capsulotomy for the femtosecond laser–assisted and phacoemulsification cataract surgery groups (Figure 1); the log-rank test confirmed no significant difference in time from surgery to PCO between the 2 groups over the time of the survival curve (P = .79). In addition, there was no significant difference in the proportion of eyes that had a Nd:YAG capsulotomy within 6 months of surgery between the femtosecond laser group and the conventional phacoemulsification group (13.2% [42 eyes] versus 9.8% [67 eyes]) (P = .11). Of the intraocular lenses (IOLs) used in this study, 1002 had a sharp or square edge and 992 were of a monofocal design. Table 1 shows other confounding variables and their relation to the incidence of Nd:YAG capsulotomy.
Several studies have suggested a higher rate of PCO requiring Nd:YAG after femtosecond laser–assisted cataract surgery,2,5 other studies have suggested lower rates of early PCO after femtosecond laser–assisted cataract surgery,6 and the recent Tran et al.7 study suggested that there is no difference in the rate of Nd:YAG laser capsulotomy between the 2 techniques. Long-term comparative cohort data are lacking,3 and this study was performed to establish whether there is a difference in the longer-term rate of Nd:YAG laser procedures between femtosecond laser–assisted cataract surgery and conventional phacoemulsification cataract surgery.
Our cohort of 319 eyes having femtosecond laser–assisted surgery and 683 eyes having coventional phacoemulsification indicates that there does not appear to be a statistical difference in Nd:YAG capsulotomy rates for symptomatic PCO over a 5-year follow-up. The rate of PCO requiring Nd:YAG capsulotomy in this study could be viewed as being higher than in other studies,6 which could be a result of the Nd:YAG capsulotomy being performed when the patient was symptomatic in the presence of PCO. This is in contrast to studies that used scientific grading methods rather than patient symptoms to measure PCO.7 In addition, the higher rate of PCO with hydrophilic IOLs is consistent with results in recent studies.7
Thus, the results suggest that the rate of symptomatic PCO requiring Nd:YAG laser capsulotomy is similar in femtosecond laser–assisted cataract surgery and phacoemulsification cataract surgery. Our results do not favor the use of one procedure over the other.
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